A method for fabricating a semiconductor device includes forming a trench in a substrate, forming a gate electrode buried over the trench to form a buried gate pattern, etching portions of the substrate on both sides of the buried gate pattern to a certain depth, performing an ion implantation process on the substrate to form source/drain junctions, and forming metal patterns over the source/drain junctions.
Legal claims defining the scope of protection, as filed with the USPTO.
1. A method for fabricating a semiconductor device, comprising: forming a trench in a substrate; forming a gate electrode buried over the trench to form a buried gate pattern; etching portions of the substrate on both sides of the buried gate pattern to a certain depth; performing an ion implantation process on the etched portions of the substrate to form source/drain junctions; forming a metal layer over the substrate structure including the source/drain junctions; and planarizing the metal layer until a surface of the buried gate pattern is exposed to form metal patterns over the source/drain junctions.
2. The method of claim 1 , wherein the substrate comprises a buried oxide layer formed inside the substrate.
3. The method of claim 2 , wherein the buried oxide layer is formed below the buried gate pattern and the source/drain junctions.
4. The method of claim 1 , the forming of the buried gate pattern further comprising, before the forming of the gate electrode buried over the trench: forming spacers over sidewalls of the trench; and forming a gate insulation layer over the surface profile of the trench.
5. The method of claim 4 , wherein the spacers comprise a nitride-based layer.
6. The method of claim 4 , wherein the gate electrode comprises a polysilicon layer.
7. The method of claim 1 , wherein the etching of the portions of the substrate to a certain depth comprises: forming a mask pattern having substantially the same line width as the trench; and etching portions of the substrate to a depth smaller than that of the trench by using the mask pattern.
8. The method of claim 1 , further comprising, after the forming of the metal patterns, forming bit line contacts over the metal patterns.
9. A method for fabricating a semiconductor device, comprising: forming a buried oxide layer in a substrate; forming a trench over the buried oxide layer in the substrate; forming a gate electrode buried over the trench to form a buried gate pattern; etching portions of the substrate on both sides of the buried gate pattern to a certain depth; forming a metal layer over the substrate structure including source/drain junctions; and planarizing the metal layer until a surface of the buried gate pattern is exposed to form metal patterns over the source/drain junctions.
10. The method of claim 9 , wherein the forming of the buried oxide layer comprises using a mask pattern to etch an oxide-based layer formed over a first silicon layer.
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May 28, 2009
April 12, 2011
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